Study of Climate Change in Uttarakhand Himalayas: Changing Patterns of Historical Rainfall

Abstract

The subject area of climate change is vast, but the changing pattern of rainfall is a topic within this field that deserves urgent and systematic attention since it affects the availability of freshwater, food production and the occurrence of water related disasters triggered by extreme events. The detection of trends in rainfall is essential for the assessment of the impacts of climate variability and change on the water resources of a region. In June 2013, several days of extremely heavy rain caused devastating floods in the region, resulting in more than 5000 people missing and presumed dead. The present study aims to determine trends in the annual, seasonal, and monthly rainfall over Uttarakhand State. Long-term (1901–2013) gridded daily rainfall data at 0.25° grid have been used. Daily rainfall data at ten grid center locations (five each in Garhwal and Kumaon divisions) in the vicinity of Haridwar, Tehri, Uttarkashi, Rudraprayag, Joshimath, Almora, Bageshwar, Munsiyari, Pithoragarh, and Rudrapur have been processed and analyzed for a period of 113 years (1901–2013). Historical trends in daily rainfall have been examined using parametric (regression analysis) and non-parametric (Mann–Kendall (MK) statistics). On the basis of regression and MK test, rising and falling trend in rainfall and anomalies at various stations have been analyzed. The result shows that many of these variables demonstrate statistically significant changes occurred in last eleven decades. Statistically significant increasing trends of annual as well as monsoon rainfall have been observed at Haridwar, Rudraprayag, Joshimath, Almora, and Munsiyari whereas statistically significant decreasing trends of monthly rainfall (August, September, and October) have been observed at Uttarkashi and Tehri stations.